1. Field of the Invention
The present invention relates to a developer unit. More particularly, the present invention relates to a developer unit having an annular cup.
2. Description of the Related Art
Photolithography is one of the ultimate steps in the semiconductor process. In photolithography, the device or the circuit pattern is coded in the photoresist as regions of exposed and unexposed photoresist. In the development step of photolithography, the exposed or unexposed photoresist is removed by the developer to define the pattern in the photoresist.
In order to perform an in-line photolithography, a commercial development step is performed by a spray/puddle process. Generally, the spray/puddle process comprises three steps. First, the developer is sprayed onto a wafer which is clamped on a vacuumed chuck and rotated. Second, the puddle development process starts with enough developer on the wafer in a static state. Third, the wafer is spun dry after development and wet cleaning.
FIG. 1 is a schematic, cross-sectional view of a conventional developer cup, which is a Mark-8 machine developed by TEL Corporation.
As shown in FIG. 1, a wafer 102 is disposed on a rotatable chuck 100. The wafer 102 can be delivered and carried by the chuck 100 via a mechanical arm. The developer is sprayed onto the wafer 102 from a developer nozzle 104. The wafer 102 and the chuck 100 are rotated with a central spindle 106 as the driving shaft while the developer is sprayed onto the wafer 102, so that the developer is uniformly distributed on the wafer 102. In order to distribute the developer on the wafer 102 evenly and quickly, many kinds of developer nozzles are designed, for example, an E square nozzle is designed. The E square nozzle is a long developer nozzle with a length as same as the diameter of the wafer to increase the sprayed range and the flux of the developer.
After the developer is uniformity sprayed onto the wafer 102, a puddle development processis performed with the wafer 102 being kept stationary. While the puddle development process is performed, the developer nozzle 104 is removed and a wash-up nozzle 108 is disposed over the wafer 102. After a duration of the development, deionized water (DI water) is sprayed to remove the developer on the wafer 102. The chuck 100 and the wafer 102 are rotated to spin dry the wafer 102 according to a centrifugal force. It is worth noting that underside rinse nozzles 110 and 112 are used to rinse the underside of the wafer 102. During development, a part of the developer flows along a rim of the wafer 102 to the underside thereof. Thus, a guide ring 116 and an external cup 118 are installed to enclose the develop cup to avoid the developer and the de-ionized water to be spilled by the centrifugal force. Furthermore, the effluent can be directed and collected to a collecting tub thereby.
Besides the TEL Mark system model, common developer machines further comprise the ACT Track model and the DNS D-SPIN 200 model, etc. The developer cup structure of the developer machines is similar to that shown in FIG. 1. FIG. 2 is a schematic, cross-sectional view of a conventional DNS D-SPIN 200 developer cup machine. As shown in FIG. 2, the chuck, the underside rinse nozzle, the underside rinse vat and the cup height adjustment screw of the DNS D-SPIN 200 are respectively denoted by the reference numerals 200, 212, 202 and 208, respectively.
The developer cups used in the above-mentioned developer machine controls a quantity of the developer required for fabrication process by way of adjusting the developing dispense of the developer and rotating the chuck. Additionally, the uniformity of the developer on the wafer is controlled by the developer nozzle, such as the E square nozzle. However, the portions of the developer splashing from the wafer leads to the consumption of the developer while the wafer is rotated. Moreover, when the puddle development process is performed while the wafer is in a static situation, portions of the developer flow away from the wafer or flow onto the underside of the wafer. Therefore, more developer is wasted.